As non-contact wireless communication techniques using a portable device such as an IC card brought in a proximity range, RFID, FeliCa (a registered trademark), NFC (Near Field Communication), TransferJet (a registered trademark), etc. are known. In these techniques, there are wireless communication by electromagnetic induction using a coil, coupler, etc. and wireless communication for transmitting and receiving electromagnetic waves with an antenna of a UHF band and the like.
In wireless communication using a UHF band, a communication distance is relatively long and communication at a distance of several 10 cm or more is possible. Therefore, if the portable device is brought close to a reader at a distance of about 10 cm, stable communication is possible. There are few limitations on antenna installation location in both of the portable device and a reader. Therefore, in readers for using a UHF band, generally, a rough position for placing the portable device is indicated by a mark or the like.
However, in wireless communication using millimeter waves over 40 GHz, a wavelength of a wireless signal is short. Therefore, the size of an antenna becomes very small. Moreover, in a millimeter wave band, generally, directivity is oriented in a specific direction so as to have a high antenna gain.
In this way, in the wireless communication using the millimeter wave band, antenna directivity is extremely high, compared to wireless communication using a UHF band. Therefore, good communication may not be performed if the portable device is placed over at a location shifted from a place-over position displayed on the portable device or the reader.